921600

Appears in sequences

• a(1) = 1; a(n) is the smallest square of the form k*a(n-1) + 1, k > 0, i.e., a(n) == 1 (mod a(n-1)), n > 2.at n=5A062926
• Numbers n such that n and its 10's complement are both squares, i.e., n and 10^k - n (where k is the number of digits in n) are squares.at n=20A068810
• Numbers k such that the numerator of Sum_{d|k} 1/d > 3*k.at n=31A069096
• a(n) = smallest positive number that occurs exactly n times as a difference between two positive squares.at n=48A094191
• a(n) = ( n*(n+2) )^2.at n=30A099761
• a(n) = n^2 * (n+1)^3.at n=15A099762
• a(n) = (n^3 - n^2)*2^n.at n=9A128985
• Smallest number having exactly n square divisors.at n=27A130279
• Squares for which no smaller square has the same number of divisors.at n=30A166721
• Product of the numbers in the Collatz (3x+1) trajectory of n, including n.at n=5A178168
• Numbers in A178168, sorted.at n=9A178169
• Smallest number having exactly t divisors, where t is the n-th triprime (A014612).at n=27A185445
• Sorted number of vertices of distinct solutions in the mix of 2 or 3 regular convex 4-polytopes.at n=29A199807
• Duplicate of A199807.at n=30A199810
• Squares that can be written as a sum of 3 distinct nonzero squares in exactly two ways.at n=18A207640
• Number of 4Xn 0..1 arrays avoiding 0 0 1 and 0 1 1 horizontally and 0 0 1 and 1 0 1 vertically.at n=13A208143
• Cyclic quadrilateral numbers: numbers m = a*b*c*d such that the integers a,b,c,d are the sides of a cyclic quadrilateral whose area and circumradius are integers.at n=9A218431
• Numbers n such that phi(sigma(k))/sigma(phi(k)) < phi(sigma(n))/sigma(phi(n)) for all k < n and n is the smallest positive integer with this property.at n=7A227927
• The greedy sequence of real numbers at least 1 that do not contain any 6-term geometric progressions with integer ratio.at n=21A235057
• Squares equal to the difference between two successive primes of the form k^2+2 in the order in which they appear in A056899.at n=7A261655